1. Field of the Invention
The invention relates to equipment for processing discharging exhaust gas, and more particularly, to enhance the desorbed effect of a volatile organic compounds (VOC) abatement system.
2. Description of the Prior Art
As high-tech products trend to higher quality, trace particles or impurities influence the yield and reliability of the products as well as the health of the laborer. Therefore, whether protecting the environment, the laborer safety issues, or product competitiveness is to be regarded, it is important that air-pollution and exhaust gas cannot neglected.
Most exhaust gases in semiconductor processing are volatile organic gases, or inorganic acid or alkali gases having large volume (>50,000 m3/hr) and low concentration (<500 ppm CH4). Therefore, now most industries use a VOC abatement system. For example, Taiwan Patent 00493056 discloses a discharging exhaust gas equipment system for dealing with large volume and low concentration VOCs. This discharging exhaust gas equipment applies two technologies: one is adsorption concentration by utilizing Zeolite or active carbon to absorb VOC gases, and another is oxidization combustion for burning the high concentration pernicious gases produced from desorbing the saturated Zeolite and active carbon having high concentration VOC gases. However, while utilizing a desorbed and oxidization combustion process, the system needs a high temperature to be effective. For example, the needed temperature is at least 150˜180° C. in the desorbed process, and the required combustion temperature needs to be at least 760° C. in the oxidization combustion process. Therefore, in the interest of saving energy and cost, some heat exchangers are added into abatement systems to enhance the temperature of desorbed and oxidization combustion processes.
However, the size and the efficiency of the heat exchanger will influence the exchanged temperature. If the exchanged temperature is not high enough, in the long-term the Zeolite and active carbon cannot obtain the desorbed temperature resulting in the efficiency of the VOC abatement system and the burned exhaust gases being decreased. Therefore, the heat exchangers should be renovated to enhance the efficiency, or temperature of the incinerator should be increased. However, needed methods incur too high of a cost and building the equipment is too difficult, so that the goal of saving cost and energy cannot be attained.